The present invention relates to a battery pack using lithium ion battery or the like, and in particular, to a battery pack comprising a charge control unit, which contains specific information for each battery and stores status information of each battery and can adequately control charging and discharging of the battery.
Small size electronic equipment and devices are widely propagated now, and batteries are used to supply electric power to these equipment and devices. Small size and large capacity sealed type battery, i.e. non-aqueous electrolytic solution type battery such as nickel hydrogen battery, lithium ion secondary battery, etc., are now used as power source for portable telephone set, lap-top personal computer, camera-integrated video recorder, etc.
In battery-using equipment, i.e. equipment where battery is attached and used, battery pack comprising different types of batteries such as nickel-cadmium battery, nickel hydrogen battery, lithium ion battery, etc. is often used depending upon each intended purpose, and it is necessary to perform charging and discharging according to the method suitable for each type of battery.
Also, even when the batteries belong to the same type, capacity of the battery may be different or properties of the batteries may differ according to active material or other material of each battery. Thus, it is necessary to identify type of each battery and to perform charging and discharging by a method suitable for each battery type.
A battery and a battery-using portable equipment are known from JP-A-10097875, in which there is provided an EEPROM memory to store information of battery types and brands, and when a battery is mounted on a battery-using equipment, it is identified from the stored information whether it can be used on the battery-using equipment or not, or charging and discharging are performed according to a method suitable for each type of battery.
Further, a portable type electronic device is known from JP-A-06310179 or JP-A-07230344. This portable electronic device has a battery pack, which comprises a storage device for storing battery status and an interface circuit to control access to the storage device from the electronic device itself.
However, in the conventional type battery pack, it has been simply proposed to provide a storage device for identifying specific information of the battery or a storage device for indicating battery status. No proposal has been made on a type of battery pack, in which battery can be placed under perfect control on the operating status of the battery from the time of manufacture of the battery pack.
It is an object of the present invention to provide a battery pack under perfect control of the battery pack operation, by which it is possible to easily carry out various tests at the time of manufacture of the battery pack, to use the results of the tests as information for the subsequent operation of the battery pack, and to apply the information for common use of battery packs having different properties such as charge/discharge capacity, charge/discharge voltage, etc.